This invention relates to an apparatus for treating seeds by applying a liquid such as a herbicide or fungicide to the seed.
Seed coating apparatuses typically utilize a cylindrical or frustoconical housing in which seed is fed into the top of the housing which is dispersed in the open interior and falls downwardly though a seed coating region in which dispersed air born droplets of coating fluid contact and coat the falling seeds.
The prior art devices utilize various means for dispersing the seed and dispensing seed coating fluid in the seed coating region.
U.S. Pat. No. 3,288,052 to Hough discloses a rotating vaned structure with an open bottom for dispersing seed. A rotating concave plate receives the fluid which is discharged over the upper lip of the plate. The plate has no features to capture the fluid and accelerate it to the speed of the plate before discharge.
U.S. Pat. No. 2,862,511 to Forsberg discloses a rotating brush for dispensing the fluid. The brush receives fluid which is hurled outwardly from the brush fibers by the centrifugal force provided by the rotation. The seed dispersing portion comprises a non-rotating cone to disperse the seed.
U.S. Pat. No. 3,912,231 to Weber and assigned to the assignor of the invention of this application, discloses a rotating plate for dispensing the fluid. The fluid is poured on the plate and is hurled outwardly by centrifugal force. Weber discloses flutes in the plate to increase the vertical distance in which droplets are hurled outwardly.
The above prior art means for dispensing the fluid leave room for improvement in the coating efficiency of the mist produced. Non-uniform droplets, droplets discharged at less than optimal velocity, uneven density of the mist in the seed treating region, difficulty in cleaning the devices, seed coating regions which extend only a minimal distance vertically, and the inadvertent spread of fluid beyond the seed coating region are all problems associated with the above apparatuses.
It is highly significant that the fungicides utilized for coating seeds are extremely expensive and can be quite toxic. In order to be optimally effective, the fungicide must efficiently coat the entire outer surface of each seed with a minimal amount of fluid. Thus, the efficiency in coating seeds, containment of the seed coating fluid in limited areas of the apparatus, and having an apparatus which is easily cleanable are highly desirable features in this type of equipment.